This invention relates to a tape transport apparatus for delivering tape and similar products at high speed and under a constant tension within a precise plane of travel. The particular embodiment disclosed herein is a tape duplicator slave of the type used to make numerous copies of an audio tape from a master tape. However, the method and apparatus disclosed in this application also has a potential for utilization in any open reel or open pancake tape transport system, audio cassette duplication, tape slitting, video or audio cassette loading.
Numerous systems are known and are in present use for duplicating audio tape at high speed. Present known systems use capstans with pressure rollers and separate motors to turn the supply and take-up hubs. This necessitates having a sensor or sensor(s) in the tape path to monitor tape tension and in some way control the torque or speed of the supply and/or take-up hub to keep all of the operating criteria within acceptable limits. For this reason, many present systems are cumbersome, complicated, in constant need of adjustment and costly to manufacture.
Other systems attempt to minimize expense by making no provision whatsoever for monitoring tape tension. However, simplicity is achieved at the cost of uncontrolled starts, stretched tape and poor playback quality of recordings.
These problems are particularly difficult to correct when winding "pancakes". The term "pancakes" is a term of art in the recording industry and refers to a package of wound tape which has a relatively small core around which is wound a single width of relatively narrow tape. The extreme width of the package in comparison with its thickness causes it to resemble a thin round disk-like object such as a dinner plate or a pancake. This term will be used frequently throughout this application and when so used refers to the object described immediately above.
Because of the extreme width of a pancake in comparison with its depth, each layer of tape must be laid precisely on top of the underlying layer. Otherwise, the tape will not unwind properly and, if not handled with extreme care, separate, causing the entire package to be ruined. When properly wound, a pancake can be grasped on its outer edge and held between the thumb and forefinger without any layer of tape moving relative to any other layer.
Known take-up pancake packing systems provide quality which varies within great extremes depending on the tape speed, type of tape or tension under which the tape is optimally wound.
Another disadvantage of present tape packing systems is the tape guides which guide the successive layers of tape onto the take-up package. Present tape guides are often flat across the tape. When the guide is a roller guide, the tape will tend to be skewed to one side or the other. Because of the flexible nature of the tape, it is difficult to guide by its edges. Yet, known systems attempt to guide the tape onto the take-up package in precisely this manner.
Therefore, it is an object of the present invention to provide an apparatus and method for transporting tape which permits delivery of the tape at high speed and under a constant tension within a precise plane of tape travel.
It is another object of the present invention to provide an apparatus and method for transporting tape which treats the tape like a flat belt and guides it with crowned rollers.
It is another object of the present invention to provide a tape transport apparatus which treats the tape as a flat belt which is wound with a driving belt which is narrower than the tape itself.
These and other objects and advantages of the present invention are achieved in the preferred embodiment of the method and apparatus described below by providing tape transport apparatus comprising a rotatably mounted tape supply, a rotatably mounted tape take-up and a rim drive belt cooperating with the tape take-up and including a guide for placing the moving tape on a moving rim drive belt. The rim drive belt is positioned to carry the moving tape to the tape take-up and apply it to the tape take-up.
Drive means are provided for rotating the tape take-up.
According to one embodiment of the invention, the guide comprises a roller having crowned drive surface for centering the rim drive belt and the tape thereon during rotation in the tape winding plane of the tape take-up for applying the tape precisely within the desired plane.
According to one embodiment of the invention, tape tensioning means are provided for maintaining a constant pre-determined tension on the tape. The tape tensioning means is adapted to rotate the tape take-up at a pre-determined slightly faster surface speed than the speed at which the tape is being supplied thereto from the tape supply.
According to one embodiment of the invention, the tape transport apparatus includes a second rim drive belt driven by the drive and cooperating with the tape supply for taking the moving tape from the tape supply and placing the moving tape onto a second rim drive belt. The rim drive belt is positioned to carry the tape from the tape supply and maintain the tape in a precise plane for subsequent delivery to the tape take-up. The second guide comprises a roller having a crown surface for centering the rim drive belt in the tape winding plane of the tape supply.
Preferably, the apparatus includes a pressure control for moving the center of rotation of the tape supply and the tape take-up as tape transport occurs to maintain contact and constant pressure between the tape supply and tape take-up, respectively,and the rim drive belt.
The method according to the present invention includes providing a rim drive belt in rim drive relation to a take-up package, applying tape from the supply package to a rim drive belt, centering the rim drive belt in the tape winding plane of the take-up package by means of a guide roller having a crowned drive surface, delivering the tape to the rim of the take-up package on the surface of the rim drive belt, driving the take-up package by rim surface contact with the drive belt, and applying the tape from the rim drive belt onto the take-up package.
According to one embodiment of the method, the rim drive belt to which the tape is applied, contacts the tape only between its two edges.
Preferably, the method includes the additional steps of providing a rim drive belt in rim drive relation to the supply package and delivering tape from the supply package to the rim drive belt.